If the directrix is a vertical line through the point (4, 0) and the vertex is located at the origin, is the parabola a vertical or horizontal parabola? Which direction does the parabola open?

Jada has a meal in a restaurant she adds up the prices listed on the menu for everything they ordered and gets a subtotal of $42.00. when the check comes, it says they also need to pay $3.99 in sales tax. what percentage of the subtotal is the sales tax

I’m still confused on how to work the percentages

Prove sin2a + cos2a - 1 / sin2a + cos2a + 1 = 1 - tana / 1 + cota